Blank Page in JSF

Question

If my code throws an exception, sometimes - not everytime - the jsf presents a blank page. I´m using facelets for layout. A similar error were reported at this Sun forumn´s post, but without answers. Anyone else with the same problem, or have a solution? ;)

Due to some requests. Here follow more datails:

web.xml

 <error-page>
        <exception-type>com.company.ApplicationResourceException</exception-type>
        <location>/error.faces</location>
 </error-page>

And the stack related to jsf is printed after the real exception:

####<Sep 23, 2008 5:42:55 PM GMT-03:00> <Error> <HTTP> <comp141> <AdminServer> <[ACTIVE] ExecuteThread: '3' for queue: 'weblogic.kernel.Default (self-tuning)'> <<WLS Kernel>> <> <> <1222202575662> <BEA-101107> <[weblogic.servlet.internal.WebAppServletContext@6d46b9 - appName: 'ControlPanelEAR', name: 'ControlPanelWeb', context-path: '/Web'] Problem occurred while serving the error page.
javax.servlet.ServletException: viewId:/error.xhtml - View /error.xhtml could not be restored.
    at javax.faces.webapp.FacesServlet.service(FacesServlet.java:249)
    at weblogic.servlet.internal.StubSecurityHelper$ServletServiceAction.run(StubSecurityHelper.java:226)
    at weblogic.servlet.internal.StubSecurityHelper.invokeServlet(StubSecurityHelper.java:124)
    at weblogic.servlet.internal.ServletStubImpl.execute(ServletStubImpl.java:283)
    at weblogic.servlet.internal.ServletStubImpl.execute(ServletStubImpl.java:175)
    at weblogic.servlet.internal.RequestDispatcherImpl.invokeServlet(RequestDispatcherImpl.java:525)
    at weblogic.servlet.internal.RequestDispatcherImpl.forward(RequestDispatcherImpl.java:261)
    at weblogic.servlet.internal.ForwardAction.run(ForwardAction.java:22)
    at weblogic.security.acl.internal.AuthenticatedSubject.doAs(AuthenticatedSubject.java:321)
    at weblogic.security.service.SecurityManager.runAs(Unknown Source)
    at weblogic.servlet.internal.ErrorManager.handleException(ErrorManager.java:144)
    at weblogic.servlet.internal.WebAppServletContext.handleThrowableFromInvocation(WebAppServletContext.java:2201)
    at weblogic.servlet.internal.WebAppServletContext.execute(WebAppServletContext.java:2053)
    at weblogic.servlet.internal.ServletRequestImpl.run(ServletRequestImpl.java:1366)
    at weblogic.work.ExecuteThread.execute(ExecuteThread.java:200)
    at weblogic.work.ExecuteThread.run(ExecuteThread.java:172)
javax.faces.application.ViewExpiredException: viewId:/error.xhtml - View /error.xhtml could not be restored.
    at com.sun.faces.lifecycle.RestoreViewPhase.execute(RestoreViewPhase.java:180)
    at com.sun.faces.lifecycle.LifecycleImpl.phase(LifecycleImpl.java:248)
    at com.sun.faces.lifecycle.LifecycleImpl.execute(LifecycleImpl.java:117)
    at javax.faces.webapp.FacesServlet.service(FacesServlet.java:244)
    at weblogic.servlet.internal.StubSecurityHelper$ServletServiceAction.run(StubSecurityHelper.java:226)
    at weblogic.servlet.internal.StubSecurityHelper.invokeServlet(StubSecurityHelper.java:124)

I´m using the jsf version Mojarra 1.2_09, richfaces 3.2.1.GA and facelets 1.1.13.

Hope some help :(

Answer 1

I think this largely depends on your JSF implementation. I've heard that some will render blank screens.

The one we were using would throw error 500's with a stack trace. Other times out buttons wouldn't work without any error for the user. This was all during our development phase.

But the best advice I can give you is to catch the exceptions and log them in an error log so you have the stack trace for debugging later. For messages that we couldn't do anything about like a backend failing we would just add a fatal message to the FacesContext that gets displayed on the screen and log the stack trace.

Answer 2

I fixed a similar problem in my error.jsp page today. This won't be exactly the same as yours, but it might point someone in the right direction if they're having a similar problem. My problem seemed to be coming from two different sources.

First, the message exception property wasn't being set in some of the servlets that were throwing exceptions caught by the error page. The servlets were catching and rethrowing exceptions using the ServletException(Throwable rootCause) constructor.

Second, in the error page itself, the original author had used scriptlet code to parse the message using String.split(message, ";"); Since the message was null this failed. I was getting a NullPointerException in my error log, along with the message "Problem occurred while serving the error page."

These two things combined to give me a blank page at the URL of the servlet that was throwing the original exception. I fixed my problem by providing my own error message when I rethrow exceptions in my servlets using the ServletException(String message, Throwable rootCause) constructor, so the error message will no longer be null. I also rewrote the error.jsp page using EL instead of scriptlet code, but that wasn't strictly necessary.

Answer 3

For a blank page on JSF 2, place a breakpoint in ExceptionHandlerWrapper.handle or a class overriding this method. In my case it was due to custom code which was a too restrictive and the error was not logged.